Visual lens



A. E. JONES Sept. 20,1932.

VISUAL LENS Filed April 11. 1929 Patented Sept. 20, 1932 UNITED mare FFEE

ALFRED E. JONES, or sroxenn, wasnrneron VISUAL LENS Application filed. April 11,

discovered that a neutralizing curve forms he basis of manufacture of such a one focus lens, such neutralizing curvebeing used to overcome the minus power gained on the con cave surface of the lens, where I insert a a colored button to protect the eyes of the wearer while observing a distant object.

More specifically, I grind a neutralizing curve of sufiicient power to neutralize and offset the power gained at the surface of the lens, the latter being composed of glass of two indexes. The body of the lens is of crown glass and the button is of flint glass and fused in the neutralizing curve. Such button may be of any desired color and the button is colored before it is fused in'the lens blank. Such button will also be located on the concave side at the top of the lens.

The accompanying drawing illustrates the lens and various stages in the process of manufacture thereof and wherein:

Figure 1 is a view showing the crown glass blank surface concave and provided with the neutralizing curve,

Figure 2 is a view similar to Figure 1 with :m the addition of the button suggested for application to the neutralizing curve,

Figure 3 is a view similar to Figure 2 but with the button fused to the neutralizing curve,

:;. Figure 4c is a view similar to Figure 3 with the button partly ground away,

Figure 5 is a view similar to Figure 4 with the but-ton ground away flush with the concave surface of the lens, and

:1: Figure 6 is a view showing the completed lens.

In carrying out the invention a blank 10 preferably of crown glass which may be colorless, white or tlnted, has a concave surface 11 ground thereon which ultimately be- 1929. Serial No. 354,351.

comes the concave surface of the complete" lens as shown in Figure 6. After this concave surface 11 is ground, the neutralizing curve as at 12 is also ground in the concave surface 11. This neutralizing curve for example may have a radius of 5.81 centimeters, being a nine curve and concave.

The button is shown at 13, being colored or tinted and having one surface 1 1 convexly curved on the same ractius as the curve 12 so as to accurately fit the same as shown in" Figure'3. In the condition of Figure 3, the blank 10 and button 13 are fused together by heat treatment into a solid blank or substan-' tially integral mass. The power gained by the fusion is on'the button and is the correct it has no projection and is flush with the con-c cave surface 11 as shown in Figures 5 and 6, after which the opposite surface of the lens as at 15 is ground away to provide the convex curvature and to form thefinished lens.

As the result of the invention, any prescription may be ground on the convex side'of the lens without trouble as I have neutralized the power gained at segment by my neutralizing curve. If this were not done, it could not be used, as it would not have a uniform power.

Obviously the neutralizing curve may be changed to conform with the index of the two kinds of glass used so as to neutralize any power gained at the surface.

It will be noted that to overcome the gain mentioned I must grind the neutralizing curve much deeper than the base curve since.

I have found that power does not increase as fast where two pieces of glass are fused together, as it does at the surface of the lens. 1

Various mathematical formulas may be used to ascertain the increase of power at the surface although the same form no part of the invention, the following examples may make the practice of the invention clearer:

Base Radius of curve Neutral: neutralizing of lens mg our I curve i I Centimeters 1. 25 l. 875 28. 18 v 2 a 1 '17, 43 53 4. 50 11.61

' "5 7.50 .6. 99 v 16 v.9 5. 31 i ",7 10. 50 4. 98 8 12. 4. 358

The invention is particularly practiced in providing the neutralizing curve on all lenses with a base curve from one to ten.

By way of example, itmay be mentioned that the indexof the crown glass 10 specifically shown is 1.523 and that the index of the flint glass button is 1.62. Thus the surface gain is minus 1.1109, whichis neutralized by the neutralizing curve.

(1) To find minus gain at outside concave surface of segment 5231.62: 26:1 This is the power at concave or outer surface of segment.

g.1109 -1:1109 surface of the button.

(2) To-find the value of the tool in diopters which must be used to grind the neutralizing curve for the segment:

. fl-dionter tool.

(3) WVhen the value of the tool is known, to find the radius of the neutralizing curve:

'.523+9.=.0581 m. or 5.81 cm.

That is, the value of thetool usedrto grind the neutralizing curve divided into the :lj-l (index less 1) of the major portion of lens gives the radius of the neutralizing curve in meters, By moving thedecimal point two face of the segment, the latter being on the concave surface of the ends. I would not necessarily neutralize all of the power gained at the surface since in some cases it is better to give the wearer better distant vision.

I claim as my invention 1. A concavo convexlens having a recess ground in the concave side thereof, a colored Difference or gain at the concave" segment of a different refractive index from the glass of which the lens is formed positioned within said recess, the curved surface between the segment and the recess being sufficient to neutralize any effect produced by the juxtaposition of the two glasses of different refractive indices.

2. A unifocal lens formed of glass of one refractive index, a recess ground in one face of said lens, a button of colored glass and having a different refractive index from said lens fused into said recess, the curvature of thebutton and the recess into which it is received being so proportioned as to neutralize any effect produced by the juxtaposition of the two lenses of different refractive indices.

In testimony whereof I affix my signature.

ALFRED E. JONES. 

